Technical Field
The present invention relates to a position measuring device that receives reflected and scattered light of a laser light with which a surface of an object is irradiated and measures a position on the surface of the object.
Related Art
A position measuring device is known in the art which irradiates a surface of a measurement object with a laser light, causes an image sensor to receive reflected and scattered light, and calculates a position on the surface of the measurement object using triangulation (e.g., see JP 2002-139311 A).
FIG. 8 is a schematic diagram illustrating a non-contact position measuring device using triangulation. As illustrated in FIG. 8, this position measuring device includes a light emitter 10 configured to emit a laser light LS1 toward a workpiece W to be measured and a light receiver 30 provided on an optical axis not parallel to an optical axis of the laser light LS1. The position measuring device also includes a projection lens 11 configured to concentrate the laser light LS1 emitted from the light emitter 10 and a light receiving lens 12 configured to image light reflected and scattered by the workpiece W on the light receiver 30. The respective placements and angles of the projection lens 11, the light receiving lens 12, and the light receiver 30 are determined according to the Scheimpflug principle.
In order for the position measuring device to measure a position of the workpiece W, the laser light LS1 is emitted from the light emitter 10 toward the workpiece W. The light receiver 30 then captures reflected and scattered light of the laser light LS1 on the workpiece W. Since the position measuring device has a disparity D between the light emitter 10 and the light receiver 30, a displacement L of the workpiece W is determined using triangulation based on position information Δx captured by the light receiver 30, a focal length f, and the disparity D.
JP 6-185978 A discloses a distance measuring device using a hologram. This distance measuring device uses a hologram that serves to image a plurality of points on the optical axis of light generated from a light source at another different points. In the distance measuring device, a light source emits light from the light source to a measurement object and a light detection unit detects light reflected from the measurement object and through the hologram. A distance on the optical axis of the measurement object is measured based on an imaging position of the light detected by the light detection unit.